ORAL SIZE PERCEPTION OF PARTICLES: EFFECT OF SIZE, TYPE, VISCOSITY AND METHOD

We investigated how different parameters affect oral size perception of small particles of SiO ₂ and polystyrene particles of varying sizes (2–230 μm). Eighteen healthy subjects assessed the size of the particles by rubbing the sample between the tongue and the palate. The importance of size and type were studied by direct scaling and forced choice ranking and the results of the two methods were compared. To assess the relative importance of the tongue and the palate in oral size perception topical anesthesia was applied. The size and characteristics of particles are of importance for perception of particle size, where hard and irregular particles are perceived as larger than soft and round particles of similar size. The two methods of size perception, direct scaling and forced ranking produce very similar results on oral size perception. Topical anesthesia of either the tongue or the palate had no significant effect.     

MECHANISMS UNDERLYING THE ROLE OF FRICTION IN ORAL TEXTURE

The role of friction in food texture sensations are reviewed with the focus on results from our own laboratory, concentrating on texture sensations that are affected by the lubricative properties (e.g., roughness and creaminess), by the viscosity (e.g., melting and thickness) and by the used thickeners (e.g., airiness and heterogeneity). A food's lubricative properties are affected by its fat content, fat droplet size, particle size and shape and thickener. Foods with lower fat contents, larger fat droplets, larger particles and specific thickeners exhibited higher friction while their creaminess and fattiness sensations, associated with good lubrication, are reduced. Roughness and dryness sensations, associated with poor lubrication, are increased. Taste and flavor compounds also affected these texture sensations, albeit via a different mechanism. Specific compounds can affect the lubricative properties of saliva resulting in friction‐related sensations, such as astringency. Astringent compounds interact with proline‐rich proteins in saliva, causing precipitation that may be sensed as discrete particles and/or increased roughness. Alternatively, the compounds may precipitate dead cells and other debris present in saliva. Astringent compounds may also directly affect the surface properties of the oral mucosa.     

LIQUID HOLDING CAPACITY AND INSTRUMENTAL AND SENSORY TEXTURE PROPERTIES OF HERRING (CLUPEA HARENGUS L.) RELATED TO BIOLOGICAL AND CHEMICAL PARAMETERS

Instrumental texture measurements done on raw herring fillets only partly describe the sensory texture of marinated herring fillets. Sensory texture parameters of marinated fillets were related to instrumental texture measurements of raw fillets by three different data analysis approaches. Uniaxial compression measurements were used as a single parameter, as compression curves or fitted to polynomials. Data from all three methods were related to sensory firmness (r = 0.310–0.366, P < 0.05). Elasticity could be predicted from the maximum compression force (r = 0.181, P < 0.05). The compression curve contained information correlating with all the measured sensory texture parameters (r = 0.102–0.310, P < 0.05), while the fitted polynomials, in addition to firmness, could predict fatty mouthfeel (r = 0.201, P < 0.05). The most information about the sensory texture was obtained from the compression curves. This study shows that the texture properties of herring are highly intercorrelated and can be regarded as a multivariate complex of parameters. The liquid holding capacity (LHC), defined as the moisture held after a low centrifuge speed expressible moisture measurement, and the texture of herring are influenced by a variety of factors, e.g., spawning time of year, gonad maturity, body size, age and lipid content (P < 0.05). Increases in body weight, age and lipid content are intercorrelated and result in marinated fillets being more firm, elastic, juicy and fatty. Decreases in these factors will give marinated fillets that are perceived to be gritty and with low intensities of firmness, elasticity, juiciness and fatty mouthfeel.     

RELATIONSHIPS BETWEEN SENSORY AND RHEOLOGICAL MEASUREMENTS OF TEXTURE IN MATURING COMMERCIAL CHEDDAR CHEESE OVER A RANGE OF MOISTURE AND pH AT THE POINT OF MANUFACTURE

Textural characteristics of 10 Cheddar cheeses with a range of moisture contents and pH values were investigated by sensory and instrumental methods, over a 9‐month maturing period. A trained panel of nine assessors described the sensory texture characteristics of the cheeses using 11 texture parameters. Instrumental parameters were derived using texture profile analysis. Relationships between sensory, instrumental, compositional and maturation properties of the cheeses were determined with the aid of principal component analysis and multiple linear regression. Nine sensory parameters significantly correlated with instrumental parameters, e.g., sensory rubbery correlated with instrumental firmness (R = 0.696, P < 0.001), chewiness (R = 0.679, P < 0.001), fracture stress (R = 0.669, P < 0.001) and springiness (R = 0.643, P < 0.001). Sensory firmness corresponded closely with instrumental firmness (R = 0.539, P < 0.001) and fracture stress (R = 0.518, P < 0.001). Sensory and instrumental texture parameters were significantly affected by changes in moisture content, pH and maturation.